One of those actors who saw a major career boost after starring in the hit fantasy series is Alfie Allen. With Game of Thrones and the time I spent there, yes, that's what most people will associate me with, but that's essentially a good thing. Some actors struggle with being defined by a single role, but Allen embraces it and sees it as a blessing. If you're in the mood for a rewatch session of Game of Thrones, you can do so on HBO Max. Allen appears as Theon Greyjoy in all eight seasons of the fantasy series.